Overnight Fleet EV Charging in Malaysia: Depot Scheduling and Off-Peak Costs
The short answer: Set a ready-by time and an energy target for each vehicle before you set a charging timer. A depot on an eligible TNB Time-of-Use (ToU) plan can move flexible charging into off-peak hours, but waiting until 10 p.m. works only if the remaining hours, shared power and vehicle charge limits can still get every early route out on time. In our worked example, a 45 kW cap falls short even though twelve bays each have a 7 kW charger.
What are TNB’s off-peak hours for fleet charging?
For participating TNB accounts in Peninsular Malaysia, weekday peak hours are 2 p.m. to 10 p.m. Weekday off-peak hours run from 10 p.m. to 2 p.m. the next day; weekends and the public holidays listed by TNB are also off-peak. Check the depot’s actual tariff category, ToU enrolment, applicable bill components and holiday calendar before programming the controller. Sabah and Sarawak use different utilities and schedules.
Operating window | TNB ToU period for enrolled accounts | Scheduling decision |
|---|---|---|
2 p.m.–10 p.m., ordinary weekday | Peak | Charge early only for vehicles that cannot meet dispatch otherwise. |
10 p.m.–2 p.m., ordinary weekday cycle | Off-peak | Move flexible work here; give each route a deadline. |
Saturday, Sunday and designated holidays | Off-peak all day | Use daytime dwell too; maintain the site power cap. |
Account without ToU | No ToU rate difference by hour | Schedule for dispatch and spare building capacity. |
Will 12 vans be ready by 6 a.m.? A worked example
Assume twelve vans are plugged in by 10 p.m., each needs 28 kWh at the battery, each can accept 7 kW AC at its bay, and AC wall-to-battery efficiency averages 90%. The depot must deliver about 373 kWh at the meter (12 × 28 ÷ 0.90). The eight-hour window requires 46.7 kW on average. The twelve 7 kW bays add up to 84 kW of charger nameplate power; that is not the available site power.
Schedule | Grid energy available by 6 a.m. | Practical result |
|---|---|---|
45 kW cap, 10 p.m.–6 a.m. | 360 kWh maximum | Short by about 13 kWh at the meter even if the cap is sustained. |
50 kW cap, same window | 400 kWh maximum | About 27 kWh theoretical headroom. Check building capacity and route deadlines. |
45 kW cap + 20 kWh before 10 p.m. | Up to 380 kWh total | About 7 kWh theoretical headroom; give the early routes first claim. |
50 kW cap, fleet plugs in at 11 p.m. | 350 kWh maximum | Short by about 23 kWh. A one-hour delay matters. |
The example uses a stable charging cap, which an actual depot may not have. Building load, phase imbalance, a vehicle’s AC limit, minimum charger current and downtime all reduce what reaches the vans. Validate each departure, not just the site total. For sizing a new incoming supply, start with EvGuru’s fleet depot electrical capacity guide.
How to schedule vans with different dispatch times
Create a route list with plug-in time, ready-by time, battery energy needed and the vehicle’s actual maximum charge rate. A 28 kWh battery top-up at a steady 7 kW grid draw takes about 4 hours 27 minutes at 90% efficiency. A controller that gives that van a lower share needs to start it earlier. Give dispatch a way to flag exceptions after the schedule is set.
Vehicle group | Charging rule | Operator check |
|---|---|---|
Early departures | Assign minimum energy and deadline first. Allow an earlier start when the window is tight. | Confirm the vans and ports are online before the shift ends. |
Later departures | Share remaining power and stagger starts. | Check the controller can defer or pause eligible sessions. |
Late return or high-mileage route | Escalate as soon as projected ready time misses dispatch. | Pre-charge, swap routes or use the recovery bay. |
Spare vehicles | Charge after dispatch-critical vehicles. | Check there is enough reserve for an unexpected route. |
How much could off-peak scheduling save?
Use grid kWh actually moved × the difference in your applicable energy rates. Do not apply a generic home rate to a depot. The table is a sensitivity example, not a TNB quote. At 250 operating nights, the example depot uses about 93,333 grid kWh. If 70% of that energy can actually move from peak to off-peak, the shifted volume is about 65,333 kWh.
Illustrative rate difference | Energy savings per 10,000 kWh shifted | Example annual energy savings |
|---|---|---|
RM0.03/kWh | RM300 | About RM1,960 |
RM0.05/kWh | RM500 | About RM3,267 |
RM0.10/kWh | RM1,000 | About RM6,533 |
This compares the energy component only. Depending on the tariff, maximum-demand or capacity/network charges, adjustments and other bill items can change the result. Compare at least one representative bill and interval load profile before and after the proposed change. A single synchronized 10 p.m. start can create a new high load even when the energy rate is lower. Set a site cap and test how chargers behave at the same time as warehouse equipment, refrigeration or other night loads.
Which EvGuru setup fits your operation?
Site need | EvGuru option to assess | Confirm before ordering |
|---|---|---|
A few dedicated vans with predictable dwell | Guru Swift Advance Type 2 AC, available in 7 kW and 22 kW versions | The local timer and current settings suit the pilot; do not assume central multi-bay orchestration. |
An OCPP AC pilot bay with shared reporting | EO Genius 2 Type 2 socketed AC, listed with OCPP | The listing is for one unit. Check vehicle cables, back-office compatibility and whether deadline-aware scheduling and site load control are included. |
Late returns or a short turnaround | Guru Agility DC range as a targeted recovery bay | Confirm vehicle CCS2 compatibility, actual vehicle intake, input power, demand effects and controls for priority use. |
Guru Swift Advance product details · EO Genius 2 product details · EvGuru commercial DC charging options.
The installed DC unit shown below is from EvGuru’s Langkawi Port project in Kedah. It is a public installation shown as a hardware example; the 12-van schedule above is a separate worked scenario.
What to test before rolling out to the whole fleet
Test | What a useful pilot records |
|---|---|
Normal night and the busiest route mix | Grid kWh, energy target met by departure, maximum site demand and charging delays. |
Late arrivals or a failed port | Which routes miss their target, how dispatch is alerted, and whether a spare vehicle or recovery bay resolves it. |
Back office or meter connection interrupted | Whether ports pause or fall back to a known safe setting; who is alerted and who restores service. |
Hand over to a different supervisor | Can someone identify a blocked port, override a route deadline and see why charging slowed? |
Ask your competent electrical professional to assess the site and verify the installation against the Energy Commission EVCS guideline. If non-fleet drivers or another company will use the depot, confirm any access, billing and licensing implications before commissioning.
Frequently asked questions
Should every depot charger start at 10 p.m.?
No. For an enrolled TNB ToU account, use 10 p.m. as the start of the weekday off-peak window. Stagger the load, then allow exceptions for vehicles that would otherwise miss dispatch. Check the actual tariff on the depot’s bill.
Can a 22 kW charger get every van ready faster?
Only if the vehicle accepts that power, the installation can supply it, and the site controller allocates it. A vehicle limited to 7 kW AC will not take 22 kW from a larger AC charger.
Can dynamic load management remove the need for a supply upgrade?
It can help if the remaining energy and charging time are sufficient. A controller shares available capacity; it cannot make up a persistent energy shortfall. Test against a busy operating night and the earliest departure.
Should we install one DC charger as a backup?
Consider it if a missed departure has a real cost and short-turn vehicles cannot recover on AC. Compare the cost and added demand with alternatives such as earlier charging, an extra AC bay, a spare vehicle or a route swap.
What does EvGuru need to assess our fleet depot?
Send vehicle models and onboard limits, daily route energy, return and dispatch times, a recent utility bill, the site’s interval load data if available, and a parking or switchboard layout. Note how many vehicles are expected in the next phase.
Request an EvGuru fleet charging assessment and share a typical busy-night dispatch schedule. Start by testing whether the existing site can meet it.
